1. Field of the Invention
The present invention relates to a thrust reverser door for a bypass type turbojet engine.
2. Related Art
Turbofan-type turbojet engines are well known in the art and typically comprise a fan at the front of the turbojet engine which directs a flow of bypass air through a gas duct bounded by the engine cowling on the inside and a fan cowling on the outside. The generally annular duct bounded by the engine cowling and the fan cowling may channel both the bypass flow and the primary exhaust gas flow downstream from the turbojet engine, or may channel only the bypass flow.
In aircraft on which the turbojet engine is mounted outside of the airframe structure, the fan cowling and the engine cowling are configured to form respectively outer and inner boundaries of the annular bypass gas flow duct and to provide aerodynamic outer surfaces to reduce drag.
FIGS. 1 and 2 illustrate a known pivoting door-type thrust reverser 2 associated with the cowling 1 of a turbofan-type turbojet engine. As illustrated in FIG. 1, the upstream portion of the cowling which defines the outer limits of a bypass flow duct 15 and which is generally concentrically arranged about the turbojet engine (not shown) generally comprises an external cowling panel and an internal cowling panel interconnected by a frame elements 6. The outer surface of the external cowling panel has an aerodynamic configuration over which the air external to the engine passes during aircraft flight. The inner surface of the inner cowling panel defines the outer boundary of the bypass flow duct 15 through which the bypass flow air passes from left to right as viewed in FIG. 1.
The cowling also comprises a thrust reverser, illustrated generally at 2, located in a reverse thrust opening between the upstream cowling portion and a downstream cowling portion 3. The thrust reverser 2 comprises a door 7 pivotally attached to the cowling so as to pivot in the opening about transverse axis 17 such that it is movable between a closed, forward thrust position, illustrated in FIG. 1, and an open, reverse thrust position in which the forward end (towards the left as viewed in FIG. 1) of the thrust reverser door 7 is moved outwardly from the cowling, while a rear portion is moved inwardly into the bypass flow duct airstream so as to redirect or deflect at least a portion of the bypass flow through the reverse thrust opening in the cowling in a direction that has a reverse thrust component.
An actuator 8 for moving the door 7 between its forward thrust and reverse thrust positions may comprise a cylinder extending through and mounted to the frame 6, and having an extendable and retractable piston rod connected to the thrust reverser door 7.
The thrust reverser door 7 has an outer door panel 9 and an inner door panel 11 joined together by structural elements 9' to form an integrated structural door 7. The forward end of the door 7 may have a deflector to maximize the efficiency of the thrust reverser when the door 7 is in the reverse thrust position. When the door is in the forward thrust position, as illustrated in FIG. 1, the outer door panel 9 is substantially flush with the external surfaces of the upstream panel and the downstream cowling portion 3. The inner door panel 11 tapers toward the outer door panel 9 at the forward end of the door 7, forming a cavity C when in the forward thrust position.
As illustrated in FIG. 2, a plurality of thrust reverser doors 7 may be incorporated into the cowling, such doors being circumferentially spaced around the periphery of the cowling. Longitudinal beam portions 18 extend axially between forward part 4 and rear part 3 of the cowling between adjacent thrust reverser doors 7 to provide structural rigidity to the cowling and to provide pivot mounting points for attaching the doors 7 to the cowling. U.S. Pat. No. 3,605,411, and French Patents 1,482,538 and 2,030,034 illustrate typical, known thrust reversers.
It is known to utilize one linear actuator per thrust reverser door affixed to the cowling and the thrust reverser door to move the door between the forward and reverse thrust positions, as illustrated in the aforementioned French Patent 1,482,538.
In all of the above mentioned thrust reversers, the thrust reverser doors comprise structurally integrated assemblies with the outer panel forming the external surface of the thrust reverser door (when in the forward thrust position) structurally joined as a unit to an inner panel. Seals 5 are typically located at the juncture of the door and the cowling. While generally satisfactory, such structurally integrated thrust reverser doors may create problems during aircraft flight since the pressure within the gas flow duct 15 is higher than the ambient air pressure surrounding the cowling. As a result of this pressure differential, the thrust reverser door is stressed and may undergo geometric deformations. Such deformations may cause gaps between the exterior surface of the integral thrust reverser door and the cowling edges defining the reverse thrust opening that seriously degrade aerodynamic performance of the cowling.